I have found that a great deal of 650 owners have been having the same frustrating problems. Difficult cold start, bad idling and the bike would just die for no apparent reason and to top it all the problem is not consistant and if you took you bike to a dealer the computer reports no problem except maybe for some odd signals from the lambda-sensor. The problem is sometimes there and sometimes not. No worries the problem is actually very simple. Its not valves or bad sensors or faulty injectors as some bmw dealers had claimed. Your fault is the throttle-valve actuator's "air circuit" that clogged up and dirty. ...So what do you mean by this??? English please!!!...
What happens is due to the tolerances on the air filter some very fine dust does go through into the air-box and engine. (Don't worry, the grain is much to fine to cause any engine damage). You will also find that there is some oil in the air-box which comes from your crank-case-ventilation. This oil mist created from the blow-by past the rings on the piston. So the dust and this oil mist mix and creates paste which accumulates in small orifices and corners. Now you will find that this paste is worst in the throttle-valve actuator's "air circuit".
What the throttle-valve actuator does it regulates the air flow to your engine at and around idle. This system is there so that the bike can compensate for variations in air pressure due to altitude change. The throttle-valve actuator is situated to the right top of the throttle body fixed by 2 screws. To fix the fault remove the throttle body and take off all electronic components off it. You should find that to the airbox side the body is a little dirty. Look in from the top onto the butterfly valve. You should see a small hole on the wall just above the butterfly valve. That is the throttle-valve actuator's "air circuit". In there is where all gunk has piled up. The best way I found to clean it, is to blow it out with high pressure water cleaner and some washing powder dissolved in water. Dry the body with compressed air and assemble and there you go. PROBLEM SOVLVED!!!
You will find that the first or 3 attempts to get the bike to start and idle is a total mess and it seems as if your bike is totally f...d! Don't stress, this is normal. The throttle-valve actuator is a PID control system with a slow time constant. In plain English the computer of the bike adapts to change. The computer has over time been adapting to continuesly closing throttle-valve actuator's "air circuit" and now suddenly its completely open again and the change is a little drastic for the computer to fix instantly. So start the bike with some throttle and keep it going for a min or to with the throttle. Switch off and start up again and repeat. By the third or 4th time the bike should start normally without throttle and idle rock steady at 1500rpm.
I have done this 3 times. Once at 55000km and 85000km om my bike and at 20000km om a face-lift dakar. Worked every time. Good luck guys, hope this helps
What happens is due to the tolerances on the air filter some very fine dust does go through into the air-box and engine. (Don't worry, the grain is much to fine to cause any engine damage). You will also find that there is some oil in the air-box which comes from your crank-case-ventilation. This oil mist created from the blow-by past the rings on the piston. So the dust and this oil mist mix and creates paste which accumulates in small orifices and corners. Now you will find that this paste is worst in the throttle-valve actuator's "air circuit".
What the throttle-valve actuator does it regulates the air flow to your engine at and around idle. This system is there so that the bike can compensate for variations in air pressure due to altitude change. The throttle-valve actuator is situated to the right top of the throttle body fixed by 2 screws. To fix the fault remove the throttle body and take off all electronic components off it. You should find that to the airbox side the body is a little dirty. Look in from the top onto the butterfly valve. You should see a small hole on the wall just above the butterfly valve. That is the throttle-valve actuator's "air circuit". In there is where all gunk has piled up. The best way I found to clean it, is to blow it out with high pressure water cleaner and some washing powder dissolved in water. Dry the body with compressed air and assemble and there you go. PROBLEM SOVLVED!!!
You will find that the first or 3 attempts to get the bike to start and idle is a total mess and it seems as if your bike is totally f...d! Don't stress, this is normal. The throttle-valve actuator is a PID control system with a slow time constant. In plain English the computer of the bike adapts to change. The computer has over time been adapting to continuesly closing throttle-valve actuator's "air circuit" and now suddenly its completely open again and the change is a little drastic for the computer to fix instantly. So start the bike with some throttle and keep it going for a min or to with the throttle. Switch off and start up again and repeat. By the third or 4th time the bike should start normally without throttle and idle rock steady at 1500rpm.
I have done this 3 times. Once at 55000km and 85000km om my bike and at 20000km om a face-lift dakar. Worked every time. Good luck guys, hope this helps
